Support is requested for continuing research on blood access devices, ultrafiltration flow meters, formed element surface concentrations for nonadhesive and adhesive surfaces and its relationship to hemodialysis, and the relationship between blood vessel permeability and atherosclerosis. Blood access devices have been implanted into twenty dogs and show promise. We are able to predict the number of platelets contacting a nonadhesive ultrafiltering surface or adhering to an adhesive wall and we will concentrate on whole blood. Because this surface concentration is proportional to the cube of the ultrafiltration velocity, we will concentrate on the permeability of the aorta.